The invention refers to a method for separating particles which are dispersed in a dispersion medium, whereby an ultrasonic standing wave is generated by means of a composite resonator within a vessel carrying the dispersion. The frequency of the wave is preferably within the neighborhood of the characteristic frequency f.sub.o. The term dispersion is used here as a general term for all kinds of disperse systems. This concerns a system consisting of two (or several) phases in which the disperse phase is finely distributed in the other one, hereinafter referred to as dispersion medium or dispersion.
Whereas the invention is applicable to all types of particles (solid, liquid or gaseous disperse phases), there is a limitation in the dispersion medium to liquids or gases. The application hereby comprises both solid (suspensions), liquid (emulsions), and gaseous particles in liquids and solid (smoke) and liquid particles (fog) in gases. Naturally, the liquid can also be a molten mass. The widest field of application are hydrosoles (particles in water) and aerosoles (particles in air).